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| United States Patent |
5,282,049
|
|
Hatakenaka
, et al.
|
January 25, 1994
|
Moving-picture data digital recording and reproducing apparatuses
Abstract
During a recording operation, when receiving compressed moving-picture data
from the moving-picture compression encoder, the code arrangement
converter rearranges the data so that the core frame data may be
distribution-recorded in a particular place on each track of the tape, for
example, in the head portion of the main data area. In normal
reproduction, the reproduced main data undergoes error correction and
deinterleaving at the format reverse-converter. The resulting date is
rearranged by the code arrangement reverse-converter to form the
compressed moving-picture data in the same arrangement in recording. This
compressed moving-picture data passes through the moving-picture expansion
decoder and appears at the output terminal. During high-speed
reproduction, for example, 9-fold speed reproduction, the main data in a
frame corresponding to one of core frames 0 to 8 is reproduced. The
resulting signal undergoes error correction and deinterleaving at the
format reverse-converter. This deinterleaved data is supplied to the local
read data arrangement circuit, which extracts one core frame of data. This
data is decoded at the moving-picture expansion decoder and supplied at
the output terminal.
| Inventors:
|
Hatakenaka; Akira (Tokyo, JP);
Imade; Shinichi (Iruma, JP);
Wakamatsu; Seiichi (Tokyo, JP);
Kishi; Kenji (Yokohama, JP)
|
| Assignee:
|
Olympus Optical Co., Ltd. (Tokyo, JP)
|
| Appl. No.:
|
831802 |
| Filed:
|
February 4, 1992 |
Foreign Application Priority Data
| Feb 08, 1991[JP] | 3-017380 |
| Mar 18, 1991[JP] | 3-052503 |
| May 02, 1991[JP] | 3-100699 |
| May 24, 1991[JP] | 3-120058 |
| May 24, 1991[JP] | 3-120344 |
| Current U.S. Class: |
386/111 |
| Intern'l Class: |
H04N 005/76; H04N 005/783 |
| Field of Search: |
358/335,310,339,133,312,342
360/33.1,32
|
References Cited
U.S. Patent Documents
| 4361849 | Nov., 1982 | Bolger | 360/10.
|
| 4672444 | Jun., 1987 | Bergen et al. | 358/140.
|
| 4774562 | Sep., 1988 | Chen et al. | 358/133.
|
| 4780761 | Oct., 1988 | Daly et al. | 358/133.
|
| 4931879 | Jun., 1990 | Koga et al. | 358/335.
|
| 4942465 | Jul., 1990 | Ohta | 358/136.
|
| 5040061 | Aug., 1991 | Yonemitsu | 358/342.
|
| 5073820 | Dec., 1991 | Nakagawa et al. | 358/133.
|
| 5136391 | Aug., 1992 | Minami | 358/312.
|
| 5140437 | Aug., 1992 | Yonemetsu et al. | 358/342.
|
| Foreign Patent Documents |
| 63-9289 | Jan., 1988 | JP.
| |
| 63-76141 | Apr., 1988 | JP.
| |
| 63-179679 | Jul., 1988 | JP.
| |
Primary Examiner: Chin; Tommy P.
Assistant Examiner: Nguyen; Huy
Attorney, Agent or Firm: Frishauf, Holtz, Goodman & Woodward
Claims
What is claimed is:
1. A moving-picture-data digital recording apparatus comprising:
picture-data forming means including:
segmenting means for segmenting digital moving-picture-data into a
plurality of segments, each of said plurality of segments having a
specified number of frames;
slicing means for slicing data in a lead frame of each of said plurality of
segments into a specified number of slices of lead frame data that
respectively have a fixed length, the lead frame being defined as a core
frame; and
compressing means for providing an in-frame-compressing of data in said
lead frame of each of said segments, and for providing an
interframe-compressing of said digital moving-picture-data in a plurality
of remaining frames of each of said plurality of segments;
said picture-data forming means forming picture-data that is reproducible
at a predetermined first speed of a recording medium;
picture-data arrangement converting means having extracting means for
extracting a plurality of slices of said lead frame data from the
picture-data formed by said picture-data forming means, said picture-data
arrangement converting means including converting means for converting an
arrangement of said picture-data formed by said picture-data forming means
wherein said extracted slices of said lead frame data, extracted by said
extracting means, are distribution-recorded in a particular place on a
plurality of tracks of said recording medium, as output second
picture-data that is reproducible at a second speed of said recording
medium, said second speed of said recording medium being higher than said
predetermined first speed of said recording medium; and
recording medium for digitally recording on said recording medium, said
picture-data formed by said picture-data forming means, after said
picture-data is converted and arranged by said converting means of said
picture-data arrangement converting means.
2. The apparatus according to claim 1, wherein said converting means of
said picture-data arrangement converting means converts the arrangement of
said picture-data formed by said picture-data forming means, such that
said slices of said lead frame data are distribution-recorded in said
particular place on each of said plurality of tracks in accordance with a
spacing between a plurality of frames reproduced during a reproduction at
said second speed.
3. The apparatus according to claim 1, wherein said converting means in
said picture-data arrangement converting means converts the arrangement of
said picture-data formed by said picture-data forming means, such that
said slices of data in said lead frame are distribution-recorded in a head
portion of a main data area of each track of said recording medium, the
head portion corresponding to said particular place on each of said
plurality of tracks.
4. The apparatus according to claim 1, wherein:
said converting means of said picture-data arrangement converting means
converts the arrangement of said picture-data formed by said picture-data
forming means, such that said slices of said lead frame data are
distribution-recorded in said particular place on each of said plurality
of tracks, each of said particular places being a local area of a main
data area on each track; and further comprising:
a reproducing head for tracing said local areas when the data recorded on
said recording medium is reproduced at said second speed.
5. The apparatus according to claim 1, wherein said converting means in
said picture-data arrangement converting means converts the arrangement of
said picture-data formed by said picture-data forming means, such that
said slices of said lead frame data are distribution-recorded in a
plurality of sub-code areas on each of said plurality of tracks, each of
said sub-code areas on each of said plurality of tracks corresponding to
said particular place on each of said plurality of tracks.
6. A moving-picture-data digital reproducing apparatus comprising:
reproducing means including:
reproduction means for reproducing a plurality of digital recording data
recorded on a recording medium;
said digital recording data being recorded on said recording medium after:
segmenting means segments digital-moving-picture-data into a plurality of
segments, each segment having a specified number of frames; and
slicing means slices data in a lead frame of each of said plurality of
segments into a specified number of slices of lead frame data that
respectively have a fixed length, said lead frame being defined as a core
frame;
picture data forming means for forming picture-data that is reproducible at
a predetermined first speed of said recording medium, said picture-data
forming means including:
compressing means for providing an in-frame-compressing of data in said
lead frame of each of said segments, and for providing an
interframe-compressing of said digital moving-picture-data in a plurality
of remaining frames of each of said segments; and
extracting means for extracting said slices of said lead frame data from
said picture-data formed by said picture-data forming means; and
arrangement converting means for converting an arrangement of said
picture-data such that said extracted slices, extracted by said extracting
means, are distribution-recorded in a particular place on a plurality of
tracks of said recording medium, as output second picture-data that is
reproducible at a second speed of said recording medium, said second speed
being higher than said predetermined first speed of said recording medium;
said picture-data forming means further including:
first picture-data forming means for forming a first plurality of
picture-data to be reproduced at said first speed, based on the digital
recording data reproduced by said reproducing means;
second picture-data forming means for forming, when said picture-data is
reproduced at said second speed, a second plurality of picture-data based
on said digital recording data reproduced from said particular place on
each of said plurality of tracks by said reproducing means; and
third picture-data forming means for forming, when said digital recording
data is reproduced at said first speed, digital moving-picture-data based
on said first plurality of picture-data formed by said first picture-data
forming means, and for forming, when said digital recording data is
reproduced at said second speed, digital moving-picture-data based on said
second plurality of picture-data formed by said second picture-data
forming means.
7. The apparatus according to claim 6, wherein said slices of said lead
frame data are distribution-recorded in said particular place on said
plurality of tracks in accordance with a spacing between a plurality of
frames reproduced at said second speed.
8. The apparatus according to claim 6, wherein said slices of said lead
frame data are distribution-recorded in a head portion of a main data area
of each of said plurality of tracks, said head portion corresponding to
said particular place on each of said plurality of tracks.
9. The apparatus according to claim 6, wherein:
said reproduction means comprises a reproducing head for reproducing data
recorded on said recording medium; and
said slices of said lead frame data, sliced by said slicing means, are
distribution-recorded in a local area of a main data area in said
plurality of tracks, said reproducing head tracing said local area a
reproduction at said second speed; and
said local area corresponds to said particular place on each of said
plurality of tracks.
10. The apparatus according to claim 6, wherein said slices of said lead
frame data, sliced by said slicing means, are distribution-recorded in a
plurality of sub-code areas on said plurality of tracks, a respective
sub-code area on each of said plurality of tracks corresponding to said
particular place on each of said plurality of tracks.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to moving-picture digital recording and reproducing
apparatuses such as digital tape recorders, and more particularly to a
moving-picture data recording and reproducing system capable of high-speed
reproduction.
2. Description of the Related Art
Digital audio tape (DAT), originally developed for audio use, is finding
wide application as an external memory in the field of computers where it
is standardized in DATA/DAT format.
In a moving-picture data recording/reproducing apparatus using helical
scanning digital tape such as DATA/DAT, tracking based on automatic track
fining (ATF) is performed during high-speed reproduction by controlling
the rotational speed of the cylinder so that the bit rate of the
reproduced signal may be equal to that for normal reproduction according
to the tape speed. For an n-fold speed reproduction, if n is odd, data on
tracks with both positive and negative azimuth angles can be reproduced at
intervals of n tracks, and if n is even, data on tacks with either a
positive or a negative azimuth angle can be reproduced at intervals of 2n
tracks.
In general, digital recording has the advantage of less degradation of
pictures during dubbing, but has the disadvantage of requiring a larger
amount of data than analog recording. Therefore, in recording
moving-picture data on a tape medium by helical scanning, even one frame
of picture data extends over several tracks, with the result that
high-speed reproduction cannot be achieved by simply increasing the tape
speed as in analog recording.
At the time of decoding compressed moving-picture data, defects in the data
heavily affect the picture quality and complicate the decoding process.
For this reason, to achieve high-speed reproduction, it is necessary to
use a recording format suitable for high-speed reproduction in recording
moving-picture data on DATA/DAT.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide
moving-picture data digital recording and reproducing apparatuses that use
a new recording/ reproducing system capable of easy high-speed
reproduction of moving-picture data.
The foregoing object is accomplished by a moving-picture data digital
recording apparatus comprising: first picture-data forming means for
receiving digital moving-picture data and forming normal-speed
reproduction picture data for normal-speed reproduction; second
picture-data forming means for receiving digital moving-picture data and
forming high-speed reproduction picture data for high-speed reproduction;
third picture-data forming means for forming digital recording picture
data for digital recording on a recording medium, out of the normal-speed
and high-speed reproduction picture data formed at the first and second
picture-data forming means, the digital recording picture data having such
a data arrangement that the high-speed reproduction picture data are
distribution-recorded in a particular place on each track of the recording
medium; and recording means for recording on the recording medium the
digital recording picture data formed at the third picture-data forming
means.
The foregoing object is also accomplished by a moving-picture data digital
reproducing apparatus comprising: reproducing means for reproducing
digital recording data, which is recorded on a recording medium and has
such a data arrangement that high-speed reproduction picture data for
high-speed reproduction is distribution-recorded in a particular place on
each track of the recording medium; first picture-data forming means for
forming normal-speed reproduction picture data for normal-speed
reproduction out of the digital recording data reproduced by the
reproducing means; second picture-data forming means for, in high-speed
reproduction, forming high-speed reproduction picture data out of the
digital recording data reproduced from the particular place by the
reproducing means; and third picture-data forming means for forming
digital moving-picture data out of the normal-speed reproduction picture
data from the first picture-data forming means during normal-speed
reproduction, and out of the high-speed reproduction picture data from the
second picture-data forming means during high-speed reproduction.
Additional objects and advantages of the invention will be set forth in the
description which follows, and in part will be obvious from the
description, or may be learned by practice of the invention. The objects
and advantages of the invention may be realized and obtained by means of
the instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part
of the specification, illustrate presently preferred embodiments of the
invention, and together with the general description given above and the
detailed description of the preferred embodiments given below, serve to
explain the principles of the invention.
FIG. 1 is a block diagram for a first embodiment of the present invention;
FIG. 2 is a schematic representation of DATA/DAT group format 1;
FIG. 3 is an illustration of track format;
FIG. 4 shows the hierarchy structure of moving-picture data handled in the
embodiment;
FIG. 5 illustrates compression encoded moving-picture data;
FIG. 6 is a table for explaining a distribution arrangement of core frame
data;
FIG. 7 shows the relationship between each frame and each slice within
group 0 of 15 slices of 9 I pictures within DATA/DAT groups 0 and 1 in a
second embodiment of present invention;
FIG. 8 shows the relationship between each frame and each slice within
group 1 of 15 slices of 9 I pictures within DATA/DAT groups 0 and 1 in the
second embodiment;
FIG. 9 is a table for I picture that is reproduced and displayed in each
slice position during triple-speed reproduction;
FIG. 10 is a table for I picture that is reproduced and displayed in each
slice position during quintuple-speed reproduction;
FIG. 11 is a table for I picture that is reproduced and displayed in each
slice position during 9-fold speed reproduction;
FIG. 12 shows particular places on the frame in which core frame data is
recorded in the first and second embodiments;
FIG. 13 is a view showing the data structure of one block of data recording
area in a third embodiment of the present invention;
FIG. 14 is an explanatory view of the tracing of the head during
ultrahigh-speed reproduction;
FIG. 15 is a view of head traces during ultrahigh-speed reproduction;
FIG. 16 is a block diagram for a fourth embodiment of the present
invention;
FIG. 17 illustrates recording format used in recording high-speed
reproduction picture data in the sub-code area;
FIG. 18 shows the state where one frame of high-speed reproduction core
frame data have been distributed and recorded in the sub-code areas on a
plurality of tracks;
FIG. 19 is a block diagram of a fifth embodiment of the present invention;
and
FIG. 20 is an illustration of the S-DAT track pattern in a sixth embodiment
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the accompanying drawings, embodiments of the present
invention will be explained.
FIG. 1 shows the construction of a first embodiment of the present
invention. For example, this embodiment may be a helical scanning tape
recorder that records moving-picture data in tape format as shown in FIG.
2. FIG. 2 schematically shows DATA/DAT group format 1. In the figure,
frame 10 is composed of a positive azimuth track followed by a negative
azimuth track. Each track 12, as shown in FIG. 3, is made up of a main
data area 14, sub-code areas 16, automatic track finding (ATF) areas 18,
and margin areas 20.
The main data area 14 is an area in which audio or video data is to be
recorded. The sub-code areas 16 are areas in which various data necessary
for main data reproduction and attendant data are to be recorded. The
former data includes the type of information recorded in the main data
area 14, the tape speed, the data sampling frequency, the quantization
rules, and the data compression rules. The latter data includes the
program time, the time code, the date and time, and the signal for program
search. The ATF areas 18 are where a tracking signal is to be recorded
which is necessary for the recording/reproducing head to trace the track
12 properly. The margin areas 20 are provided between the main data area
14 and the AFT areas 18 and between each ATF area 18 and each sub-code
area 16, respectively, so that independent after recording can be
preformed.
In FIG. 1, the camera section (not shown) supplies moving-picture data to
the input terminal 22 in the form of digital signal. Layer (A) in FIG. 4
represents the video sequence layer of the digital moving-picture data
supplied to the input terminal 22. The digital moving-picture data has the
picture sequence as shown in this layer (A).
The digital moving-picture data supplied to the input terminal 22 is
compression-encoded by a moving-picture compression encoder 24. This
encoder 24, as disclosed in U.S. Pat. No. 4,780,761 or U.S Pat. No.
5,073,820, for example, performs compression encoding, such as distributed
cosine transformation (DCT) and two-dimensional Huffman coding. FIG. 5 is
a schematic view of moving-picture data compression-encoded by the
moving-picture encoder 24. In the figure, the core frame contains data on
a moving-picture frame obtained by compressing only the information within
one moving-picture frame, and the interframe contains data on a
moving-picture frame obtained by compressing the information within two or
more moving-picture frames.
The compression-encoded output of the moving-picture encoder 24 will be
explained in more detail. In layer (B) of FIG. 4, the compression-encoded
output pictures of the moving-picture encoder 24 are sequenced so as to
correspond to the sequence of the original pictures in layer (A).
Layer (C) of FIG. 4 is a layer of groups of pictures (GOPs), each GOP
having nine pictures except that the first GOP is made up of seven
pictures.
Layer (D) is a picture layer. In the figure, characters I, B, P represent I
picture, B picture, and P picture, respectively. I picture is an encoded
picture capable of being decoded irrespective of the past and the future
pictures and corresponds to the core frame. P picture is an encoded
picture using the motion compensation prediction based on the past I
picture or P picture, and B picture is an encoded picture using the motion
compensation prediction based on the past or future I picture or P
picture. These P picture and B picture correspond to the interframe. In
this embodiment, each picture includes 15 slices.
Layer (E) is a slice layer, where a value by which the quantization matrix
is multiplied, the quantizer scale (QS), is updated by slice.
Layer (F) is a macroblock layer, where Y represents a luminance component
and Cb and Cr indicate color-difference components, each color-difference
component being half as large as the luminance component in the lateral
and longitudinal directions. Motion compensation prediction is made by
macroblock, and QS is also updated by macroblock.
Layer (G) is a block layer. As seen from the figure, one block of
16.times.16 pixels is composed of four Y blocks, one Cb block, and one Cr
block. The block is used as a unit in DCT calculation or zigzag scanning.
In FIG. 1, the moving-picture data compression-encoded at the
moving-picture compression encoder 24 is supplied to a code arrangement
converter 26. This converter 26 converts the arrangement of the encoded
data so that the high-speed reproduction data (core frame data) may be
recorded in particular places as described later.
The encoded data whose arrangement has been converted at the code
arrangement converter 26 is supplied to a format converter 28, which
converts it into recording data that follows the recording format
complying with the standards of the digital tape recorder used. What the
format converter 28 does includes addition of C1, C2, and C3
error-correction codes and transformation into DATA/DAT format (or
interleaving). After having been modulated at a recording/reproducing
circuit 30, the recording data is supplied via a recording amplifier (not
shown) to a recording/reproducing rotary head 32, which records it in the
main data area 14 of a magnetic tape 34.
After the signal sensed by the rotary head 32 has been demodulated at the
recording/reproducing circuit 30, it is deinterleaved and error-corrected
at a format reverse-converter 36. The output signal of the
reverse-converter 36, after having been converted into the encoded data in
the original sequence at a code arrangement reverse-converter 38, is
decoded by a moving-picture expansion decoder 40. The resulting signal is
supplied as a moving-picture signal at the output terminal 42 in the
sequence shown in layer (A) of FIG. 4.
During high-speed reproduction, a local read data arrangement circuit 44
concatenates pieces of data read from the particular recording places
according to the speed of high-speed reproduction, the data being supplied
from the format reverse-converter 36. It then produces an encoded data
according to the high-speed reproduction speed and supplies it to the
moving-picture expansion decoder 40.
The operation of this construction will be explained in detail.
First, during a recording operation, the code arrangement converter 26,
when receiving a compressed moving-picture data as shown in FIG. 5 from
the moving-picture compression encoder 24, changes the arrangement of data
so that the core frame data may be recorded in particular places on the
tape. The particular places correspond to the frame portions in FIG. 6.
The number of blocks in each frame portion is previously determined
depending on the amount of data in the core frame. To the shaded portion
46 of FIG. 6, however, the core frame data is not allocated because it
contains C3 error-correction code added by the format converter 28 at the
later stage.
During normal reproduction, reproduced main data is error-corrected and
deinterleaved by the format reverse-converter 36, and is changed by the
code arrangement reverse-converter 38 into compressed moving-picture data
that is rearranged in the same sequence as that in recording shown in FIG.
5. This moving-picture data is supplied via the moving-picture expansion
decoder 40 at the output terminal 42.
In the case of 9-fold speed reproduction, the main data of frames
corresponding to one of core frames 0 to 8 in FIG. 6 is reproduced, and
then error-corrected and deinterleaved at the format reverse-converter 36.
This deinterleaved data is supplied to the local read data arrangement
circuit 44, which takes out data from one core frame. This data is decoded
by the moving-picture expansion decoder 40 and the resulting signal is
supplied at the output terminal 42.
In triple-speed reproduction, the main data of frames corresponding to one
of the following three-core groups of core frames 0, 3, 6, and core frames
1, 4, 7, and core frames 2, 5, 8 among combinations of core frames 0 to 8
in FIG. 6, is reproduced, and then error-corrected and deinterleaved by
the format reverse-converter 36. This deinterleaved data is supplied to
the local read data arrangement circuit 44, which takes out data from
three core frames. These data are decoded at the moving-picture expansion
encoder 40 and then supplied at the output terminal 42.
As noted above, in this embodiment, moving-picture data that has been
compressed in units of two groups in DATA/DAT group format 1, is recorded
in 81 moving-picture frames. At that time, distributing and recording 9
core frames at intervals of nine frames allows high-speed reproduction
with 9-fold speed or triple speed and the reproducing of one or three core
frames per two groups.
For high-speed reproduction with n-fold speed, by allocating the number of
blocks according to the data volume of core frame to consecutive areas of
positive azimuth tracks located at intervals of n frames, core frame data
is distributed and recorded as follows, where F indicates the frame number
in the group:
______________________________________
Core frame 0
.fwdarw. F.sub.0,
F.sub.n, F.sub.2n,
. . .
Core frame 1
.fwdarw. F.sub.1,
F.sub.n+1,
F.sub.2n+1,
. . .
Core frame 2
.fwdarw. F.sub.2,
F.sub.n+2,
F.sub.2n+2,
. . .
. . .
. . .
Core frame (n-1)
.fwdarw. F.sub.(n-1),
F.sub.n+(n-1),
F.sub.2n+(n-1),
. . .
______________________________________
When data recorded as described above is reproduced at n-fold speed, core
frame data for one of core frames 0 to (n-1) will be reproduced. If n/2,
n/3, . . . are integers, respectively, reproduction at n/2-fold speed,
n/3-fold speed, . . . allows reproduction of 2, 3, . . . pieces of core
frame data for core frames 0 to (n-1).
Although in the above embodiment, the compressed moving-picture data has
such format that a fixed core frame is provided for every nine
moving-picture frames, and all core frames are used for high-speed
reproduction, it is not always necessary for all core frame data to be
recorded in the particular places for high-speed reproduction. For
example, only some core frames may be recorded in the particular places
for high-speed reproduction, or several core frames may be recorded in
this place, allowing duplication. In the first embodiment, high-speed
reproduction, normal or reverse, may be made at any speed, not limited to
triple speed or 9-fold speed.
A second embodiment of the present invention will be explained. While in
the first embodiment, core frame data is distributed and recorded in
particular places on the tape so as to mate with intervals of frames to be
reproduced during high-speed reproduction, in the second embodiment,
slices of core frame data are distributed to the individual frames to
record them in particular places.
Specifically, in a recording operation, when moving-picture data (layer (A)
data) as shown in FIG. 4 is supplied to the input terminal 22, the
moving-picture compression encoder 24 performs DCT on I picture in blocks.
It carries out linear quantization and two-dimensional Huffman coding in
its first passing to compute the amount of codes generated in blocks and
slices. Then, the optimum QS value and the amount of codes allocated to
each block are determined based on this calculated amount of codes
generated and the amount of codes allocated to each slice (a fixed value
for I picture) for the first passing. In the second passing, linear
quantization is carried out using the optimized QS. The two-dimensional
Huffman coding is performed in the order of zigzag scanning, while
terminating the encoding, if necessary, so that the result may be within
the amount of codes allocated to each slice.
After having performed motion compensation prediction in macroblocks for P
picture and B picture, the moving-picture compression encoder 24 carries
out DCT in blocks. Motion compensation of P picture is made only for the
forward direction (motion compensation for the past picture), and motion
compensation of B picture may be made for any of the forward direction,
the backward direction (motion compensation for the future picture), and
both directions.
Next, the moving-picture compression encoder 24 performs linear
quantization and two-dimensional Huffman coding in the first passing only.
It then compares the target amount of codes with the amount of codes
generated, to determine the next target amount of codes and QS for each of
P picture and B picture.
The amount of codes allocated in slices to each picture in the second
embodiment is as follows:
I picture--1280 bytes (fixed)
P picture--460 bytes (initial value)
B picture--115 bytes (initial value)
The moving-picture data compression-encoded as described above is supplied
to the code arrangement converter 26. The code arrangement converter 26
changes the arrangement of data so that the slices of I picture may be
distributed to each frame on the tape. At this time, the moving-picture
data of 9 GOPs are recorded in units of two groups in DATA/DAT format.
FIGS. 7 and 8 show the relationship between each frame and each slice of 9
I pictures within the group. In the figures, it is assumed that symbols I0
to I8 are the numbers of I pictures, and S0 to S14 are the numbers of
slices. 86400 bytes of audio data for two groups are recorded
simultaneously, and data of P and B pictures is recorded in the remaining
part of the tape on which I picture and audio data have been recorded.
Therefore, because of variations in the amount of codes, The nine GOPs do
not always fit in two groups, with the result that there may be a case
where the group boundary does not agree with the GOP boundary.
Then, the format converter 28 adds error correction parity to the encoded
data, whose arrangement has been converted at the code arrangement
converter 26, and then interleaves it. The results are supplied as
DATA/DAT main data to the recording/reproducing circuit 30.
During normal reproduction, the format reverse-converter 36 performs error
correction and deinterleaving on the reproduced main data, and supplies
the resulting encoded data to the code arrangement reverse-converter 38.
The code arrangement reverse-converter 38 converts the I picture data,
arranged so as to be distributed to each frame, and the B and P picture
data into those in the original sequence, and supplies the resulting
encoded data to the moving-picture expansion encoder 40. The expansion
encoder 40 decodes the encoded data into moving-picture data and supplies
it at the output terminal 42.
During high-speed reproduction, data in tracks at intervals corresponding
to the reproduction speed is reproduced. The format reverse-converter 36
performs error correction and deinterleaving on this data and supplies the
resulting data to the local read data arrangement circuit 44. The local
read data arrangement circuit 44 picks out the slices of I picture from
the input data.
FIGS. 9 to 11 show the I picture number of each slice reproduced at this
time. FIG. 9 shows the numbers for triple speed, FIG. 10 for quintuple
speed, and FIG. 11 for 9-fold speed. In the figure, for example,
".times.3-0" means that the head traces frame 0 at triple speed.
The I picture slice data picked out at the local read data arrangement
circuit 44 is decoded at the moving-picture expansion decoder 40 and
supplied as moving-picture data at the output terminal 42.
As explained above, in the second embodiment, I picture can be reproduced
at high speeds in slices according to various speeds, by
compression-encoding moving-picture data in slices of I picture in the
form of fixed length, and distributing and recording the slices of 9 I
pictures on each frame in units of two groups in DATA/DAT group format 1.
While in the above embodiment, a GOP is composed of 9 pictures and a
picture is made up of 15 slices, they may be composed of in other ways. In
addition to triple speed quintuple speed and 9-fold speed used in the
embodiment, other speeds may be used in high-speed reproduction, normal
and reverse. Further, the amount of codes allocated in compression
encoding in the second embodiment may be changed. The amount of codes may
be controlled in another way.
In the first and second embodiments, various places can be thought of as
particular places on which core frame data is distribution-recorded.
For example, as shown in FIG. 12, they may be the head portion 48 of each
frame 10.
By investigating the course on the format along which the head is to trace
during high-speed reproduction, and then distribution-recording core frame
data on the course, ultrahigh-speed reproduction is possible. This will be
explained as a third embodiment of the present invention, referring to the
accompanying drawings.
In FIG. 1, the moving-picture compression encoder 24 segments the input
moving picture data, in units of a specified number of frames, into
blocks. At this time, the beginning frame data within a block is performed
data compression, which is complete in the frame, that is, the in-frame
data compression to form core frame data. Interframe compression is
performed on the data in the remaining frames within the block, using
motion compensation or interframe differential. When one block of data is
compressed, the amount of codes is controlled so that the data amount in
one block may be a specified amount. The compressing process within the
block is continuously performed.
The encoded data from the moving-picture compression encoder 24 is supplied
to the code arrangement converter 26. When the encoded data is actually
recorded, this converter 26 changes the arrangement of the encoded data in
a specified sequence so that core frame data may be distribution-recorded
in particular places or local areas on the discrete tracks in a manner
that allows reading in high-speed reproduction.
As shown in FIG. 13 during normal constant-speed reproduction, the head 32
can trace the track 12 sequentially and reproduces the data recorded on
all tracks 12. In ultrahigh-speed reproduction, however, the trace 50 of
the head 32 can pass through only the local areas 52 of the discrete
tracks shown by shaded portions. For this reason, one block recording area
is determined as shown in the figure, and core frame data is
distribution-recorded on the local areas 52.
The encoded data from the code arrangement converter 26 is supplied to the
format converter 28, which forms recording data according to the recording
format. The recording format conforms to the standards of the digital tape
recorder used.
The recording data from the format converter 28 is modulated at the
recording/reproducing circuit 30, and then is recorded on the magnetic
tape 34 with the rotary head 32.
The recorded data is reproduced with the rotary head 32. FIG. 14 shows how
the head 32 traces the tape during ultrahigh-speed reproduction. Because
of azimuth recording, +tracks and -tracks 12 are located side by side
alternately. Here, angle .theta..sub.N is an angle at which the head trace
50 crosses the tape transport direction during ultrahigh-speed
reproduction and .theta..sub.r is an angle at which the head trace 50
meets the tape transport direction during normal reproduction. T.sub.n is
the noise bar period, T.sub.o the on track time, T.sub.p the PLL pull-in
time, T.sub.r the data read enable time, and T.sub.p the signal waveform
interference time. For the local areas 52 on the tracks readable during
ultrahigh-speed reproduction, the time when data can be read is the time
T.sub.r. If the on track coefficient a is a=T.sub.o /T.sub.n, T.sub.r will
be:
T.sub.r =aT.sub.n -T.sub.p
The pieces of data read during the time T.sub.r can be concatenated to one
another to form core frame data. Each parameter depends on the recording
and reproducing system, and is determined by a suitable equation
accordingly.
When the data in the shaded portion in FIG. 14 is read out, the number of
revolutions of the cylinder (not shown) is controlled so that the reading
bit rate may be equal to that of normal reproduction.
FIG. 15 illustrates the tracing of the head during ultrahigh-speed
reproduction. To increase the tape transport speed V.sub.t to N-fold speed
for ultrahigh-speed reproduction, the number of cylinder revolutions will
be controlled so as to follow the equation:
Number of cylinder revolutions=(60/T.sub.c).times.(tape winding rate)
where T.sub.c is the time during which the tape 34 is in contact with the
head 32. Making the bit rate in ultrahigh-speed reproduction equal to that
in normal reproduction means that their relative speeds are made equal. If
the relative speed in still reproduction is V.sub.ro and the still angle
is .theta..sub.o, the relative speed V.sub.Nrr during ultrahigh-speed
reproduction will be:
V.sub.Nrr ={V.sub.ro.sup.2 -2V.sub.ro NV.sub.t .multidot.cos.theta..sub.o
+(NV.sub.t).sup.2 }.sup.1/2 .times.cos(.theta..sub.N' -.theta..sub.r)
where .theta..sub.r is the track angle in normal reproduction, and
.theta..sub.N ' the track angle in ultrahigh-speed reproduction. The
relative speed V.sub.ro is controlled so that the relative speed V.sub.Nrr
may equal the relative speed in normal reproduction. Because the relative
speed V.sub.ro is V.sub.ro =L.sub.to /T.sub.c with the trace length
L.sub.to being constant in still reproduction, the relative speed V.sub.ro
is varied by controlling the contact time T.sub.c. Controlling the contact
time T.sub.c means that the number of cylinder revolutions is changed
according to the above equation.
After the data reproduced at an ultrahigh speed at the
recording/reproducing circuit 30 of FIG. 1 has undergone format
reverse-conversion at the format reverse-converter 36, it is supplied to
the local read data arrangement circuit 44, which concatenates the pieces
of data read from the discrete areas to reproduce a piece of core frame
data. This reproduced data is supplied to the moving-picture expansion
encoder 40, which expands the data. Then, core frame picture data appears
at the output terminal 42.
As noted above, with the third embodiment, it is possible to reproduce the
core frame data of recorded moving picture data even when the tape is
transported at an ultrahigh speed. This allows video high-speed searching
even when moving pictures are recorded on magnetic tape in the form of
compressed data.
Although various places in the main data area 14 have been explained so far
for particular places to which core frame data is distribution-recorded,
the sub-code areas 16 may be used. This will be described in detail as a
fourth embodiment of the present invention, referring to the accompanying
drawings.
In the fourth embodiment, picture data for normal-speed reproduction is
recorded in the main data area 14, whereas picture data for high-speed
reproduction (core frame data) and various attendant information are
recorded in the sub-code areas 16. Picture data for high-speed
reproduction is recorded in the sub-code areas 16 by repeatedly recording
the same signals on a plurality of tracks in succession.
Because the data for high-speed reproduction recorded in the way described
above is recorded in the sub-code areas 16, this high-speed reproduction
data can be reproduced during high-speed reproduction.
The fourth embodiment will be explained, using a case where compressed
moving-picture data is recorded on DATA/DAT.
FIG. 16 shows the construction of the fourth embodiment. For simplicity of
explanation, description will focus exclusively on what is different from
the construction of FIG. 1. The moving-picture compression encoder 24
outputs a moving vector signal as well as compression-encoded
moving-picture data.
A scene change sensing circuit 54 senses whether or not there is any scene
change based on the magnitude and direction of the moving vector supplied
from the moving-picture compression encoder 24. Based on the record
starting signal or the signal from the scene change sensing circuit 54, a
core frame extracting circuit 56 picks out core frame picture data, which
is required to be recorded for high-speed reproduction, from the
moving-picture data compression-encoded at the moving-picture compression
encoder 24. A frame buffer memory 58 for picture data is used to store
high-speed reproduction pictures for recording.
The code arrangement converter 26 mixes the high-speed reproduction picture
data stored in the frame buffer memory 58 with the encoded moving-picture
data from the moving-picture compression encoder 24 and arranges the
resulting data so that the high-speed picture data may be recorded in a
particular place of the track 12 or the sub-code areas 16.
A signal selector switch 60, according to the reproduction mode signal,
selectively supplies the decoding output of the moving-picture expansion
decoder 40 to the output terminal 42 and the high-speed reproduction frame
memory 62. The high-speed reproduction frame memory 62 stores the decoded
picture data supplied from the moving-picture expansion decoder 40 via the
signal selector switch 60, and supplies it as the picture signal for high
speed reproduction at the output terminal 42 until the next picture data
is received.
The moving-picture expansion decoder 40 is designed to change the
moving-picture expansion system between the normal reproduction mode and
the high-speed reproduction mode.
The operation of this arrangement will be explained.
First, how moving-picture data is recorded will be described. The original
signal of the moving picture input at the input terminal 22 undergoes
I-frame compression, P-frame compression, and B-frame compression
sequentially at the moving-picture compression encoder 24, as shown in
layer (B) of FIG. 4. For example, it is assumed that the amount of codes
for a core frame after compression is 16K bytes, and the amount of codes
for one group (9 frames) is 48K bytes (the compression rate of effective
pixels to the amount of data is approximately 1/130 in CCIR rec. 601).
Then, the compression-encoded moving-picture data passes through the code
arrangement converter 26, and is added with the error correction code C3
according to the DATA/DAT format at the format converter 28. The format
converter 28 also interleaves the resulting signal, adds error sensing and
correction codes C1 and C2 to the interleaved signal, and converts it into
the DATA/DAT main data format. The signal thus obtained is modulated at
the recording/reproducing circuit 30, passes through a recording amplifier
(not shown), and is recorded in the main data area 14 of the magnetic tape
34 with the rotary head 32.
When recording of high-speed reproduction pictures is required in response
to the record starting signal or the scene change occurrence signal from
the scene change sensing circuit 54, the core frame extracting circuit 56
picks out one frame of I-frame data from the moving-picture data
compression-encoded at the moving-picture compression encoder 24, and
store it in the frame buffer memory 58. The code arrangement converter 26
mixes the high-speed reproduction picture data in the frame buffer memory
58 with the moving-picture data encoded at the moving-picture compression
encoder 24 and arranges the results so that the high-speed reproduction
picture data may be recorded in a particular place of the track 12 or the
sub-code areas 16. The data to be recorded in the sub-code areas 16 is
interleaved and added with an error correction code at the format
converter 28. This converter 28 also adds to this data attendant
information including the synchronous signal, ID code, frame address, and
time base signal, and converts the resulting data into that in the
DATA/DAT sub-code format. This converted data passes through the
recording/reproducing circuit 30 and is recorded on the magnetic tape 34
with the rotary head 32.
FIG. 17 illustrates the recording format used in recording high-speed
reproduction picture data in the sub-code areas 16. In the figure, a
portion indicated by reference character A is the main data area 14 in
which reproducible data is to be recorded, and a portion indicated by
reference character B is the sub-code areas 16 in which high-speed
reproducible data is to be recorded.
As shown in FIG. 17, the trace 50 of the rotary head 32 during high-speed
reproduction inclines at an angle to the recorded track 12. When the speed
of high-speed reproduction exceeds a specific value, all signals in the
sub-code areas 16 cannot be reproduced. The tape speed at this time is
assumed to be V.sub.g. Further, in high-speed reproduction, the readable
tracks 12 in the sub-code areas 16 are discontinuous. If readable track
intervals is N.sub.h, the track interval N.sub.h becomes maximum when the
tape speed is V.sub.g.
The amount of codes that can be recorded in the sub-code areas 16 is as
little as approximately 1/5 of the amount of codes in the main data area
14. To record compressed core frame picture data in the sub-code areas 16,
several to tens of tracks are required.
One frame of high-speed reproduction core frame data is
distribution-recorded in the sub-code areas 16 of a plurality of tracks at
track intervals N.sub.h as shown in FIG. 18. The picture data for the same
high-speed reproduction is recorded the sub-code areas 16 of the tracks
fitting in the track interval N.sub.h.
The reproduction of the moving-picture data recorded in the magnetic tape
34 will be explained.
First, reproduction at a normal speed will be described. The signals sensed
by the recording/reproducing rotary head 32 in the sub-code areas 16 and
main data area 14 are amplified at the recording/reproducing circuit 30.
This circuit 30 also performs waveform equalization, detection, and
demodulation of the amplified signals. After these signals have been
deinterleaved and error-corrected, they pass through the code arrangement
reverse-converter 38 and are demodulated at the moving-picture expansion
decoder 40. Then, the demodulated moving-picture signal is supplied via
the signal selector switch 60 at the output terminal 42 in the order shown
in layer (A) of FIG. 4.
High-speed reproduction will now be explained. The signal sensed by the
rotary head 32 in the sub-code areas 16 during high-speed reproduction
with a tape speed of V.sub.g or less, undergoes amplification, waveform
equalization, detection, and demodulation at the recording/reproducing
circuit 30. Then, after the format reverse-converter 36 has deinterleaved
and performed error correction on the demodulated signal, the code
arrangement reverse-converter 38 separates the data stored in the sub-code
areas 16, and supplies it to the local read data arrangement circuit 44.
This circuit 44 concatenates the pieces of data from the code arrangement
reverse-converter 38 and supplies the result to the moving-picture
expansion decoder 40, which decodes it into the core frame data. The
decoded moving-picture signal passes through the signal selector switch 60
and is stored in the high-speed reproduction frame memory 62, which
supplies it as the high-speed reproduction picture signal at the output
terminal 42 until the next picture data is received.
Although in the fourth embodiment, a GOP layer is made up of 9 frames, it
may be composed of in other ways. Allocation of I-frame, P-frame, and
B-frame in the embodiment are illustrative and not restrictive.
While in the first to fourth embodiments, core frame data is used as
high-speed reproduction picture data, other types of data may be used in
the present invention. For example, it may be possible to form high-speed
reproduction data different from normal compression-encoded moving-picture
data, out of the input digital moving-picture data and then record it in
particular places as described earlier.
When high-speed reproduction data is recorded in the head place of the main
data area 14 of each frame 10 as shown in FIG. 12, the picture data
recording area decreases accordingly. Because the high-speed reproduction
data is used mainly for retrieval, even very rough picture quality is
acceptable. For this reason, curtailing sub-samples would create no
problem. When rough representation serves the needs, retrieval is possible
using monochromatic pictures, omitting color difference components. In
this way, compressing retrieval pictures as much as possible to record
them in as many tracks as possible enables high-speed reproduction
according to various speeds. Alternately recording the luminance signal
and color-difference signal allows color display in double-speed
reproduction and monochromatic display in high-speed reproduction at a
speed faster than the double speed.
FIG. 19 is a block diagram of a fifth embodiment of the present invention,
where high-speed reproduction data is formed separately. In the figure,
what is different from the construction of FIG. 1 is an encoder 64 that
forms high-speed reproduction picture data and a high-speed reproduction
decoder 66. Because high-speed reproduction picture data must be
reproduced independently within one frame, the high-speed encoder 64
extracts only the luminance component from the data supplied to the input
terminal 22, and performs sub-sampling to compress data substantially.
In normal reproduction, the signal from the recording/reproducing rotary
head 32 passes through the recording/reproducing circuit 30, format
reverse-converter 36, and code arrangement reverse-converter 38, and
reaches the moving-picture expansion decoder 40, which expands the
picture. During high-speed reproduction, the signal from the
recording/reproducing rotary head 32 goes through the
recording/reproducing circuit 30, format reverse-converter 36, and local
read data arrangement circuit 44, and enters the high-speed reproduction
decoder 66, which expands the picture.
In this way, addition of high-speed reproduction data allows high-speed
reproduction covering various speeds.
While in FIG. 12, high-speed reproduction data is added to all tracks, it
may be added at intervals of several tracks. In this case, if the track
interval is N, high-speed reproduction will be made at intervals of an
integer multiple of N.
When high-speed reproduction picture data is recorded at intervals of 4
tracks (N=2), alternate recording of color difference and luminance
enables color reproduction in double-speed reproduction and monochrome
reproduction in quadruple-speed reproduction or faster. In this case, at
the doubled speed, the picture changes only once for two frames.
Monochrome high-speed scanning can be performed only on a quadruple speed
basis.
While in the first to fifth embodiments, DATA/DAT group format 1 is used,
group format 0 may be used. The present invention may be applied to
apparatuses with a high transfer rate compatible with DATA/DAT
multiple-speed and other helical scanning types of digital tape recorders.
Although in the previous embodiments, the helical scanning R-DAT is used,
the present invention may be used to digital tape recorders such as
S-DATs.
The S-DAT will be described below.
FIG. 20 shows a temporary track format of the S-DAT.
A large difference between the S-DAT and the R-DAT is that 20 tracks are
simultaneously recorded by a multichannel head in the S-DAT. Each channel
is recorded in units of 240 bits=one frame. As portions corresponding to
the main data and sub code areas of the R-DAT, 16 bits of frame=240 bits
are used for sub code, and 192 bits thereof are used for main data and a
C2 parity. The sub code capacity of the S-DAT is 1/2 that of the R-DAT.
The S-DAT has an AUX track which can be used as a sub code area. When
high-speed reproduction image data is recorded on the AUX track,
high-speed reproduction of an image can be easily performed without
performing any specific tracking unlike in the R-DAT. However, when
high-speed reproduction is performed in the S-DAT, a data rate during
reproduction may be increased to fall outside the range of an IC band for
signal processing and the like. In order to prevent this inconvenience, a
high-speed reproduction signal need only be recorded on the AUX track at a
data rate of 1/(multiple of high-speed reproduction rate).
Additional advantages and modifications will readily occur to those skilled
in the art. Therefore, the invention in its broader aspects is not limited
to the specific details, and representative devices, shown and described
herein. Accordingly, various modifications may be made without departing
from the spirit or scope of the general inventive concept as defined by
the appended claims and their equivalents.
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